<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <!-- 最新版本的 Bootstrap 核心 CSS 文件 -->
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u"
        crossorigin="anonymous">

    <!-- 可选的 Bootstrap 主题文件（一般不用引入） -->
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap-theme.min.css"
        integrity="sha384-rHyoN1iRsVXV4nD0JutlnGaslCJuC7uwjduW9SVrLvRYooPp2bWYgmgJQIXwl/Sp" crossorigin="anonymous">
    <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.js"></script>
    <!-- 最新的 Bootstrap 核心 JavaScript 文件 -->
    <script src="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa"
        crossorigin="anonymous"></script>

    <title>作业</title>
    <style>div{border: 45px solid rgb(252, 252, 252);background-color: aquamarine}</style>
</head>

<body>
    <div class="input-group">
        <input type="text" class="form-control">
        <span class="input-group-addon"><a class="glyphicon glyphicon-search"></a></span>
    </div>

    <div class="col-md-4">
        <h2>Sleek</h2>
        <p> Lorem ipsum dolor sit amet, consectetur adupiscing elt Aenean phairetra vanus maximuseCras cond imentum portotor cnima egestas,Suspendhsse potenai</p>
        <p><a class="btn btn-default" href="#" role="button">Read More</a></p>
    </div>
    <div class="col-md-4">
        <h2>Responsive</h2>
        <p> Lorem ipsum dolor sit amet, consectetur adupiscing elt Aenean phairetra vanus maximuseCras cond imentum portotor cnima egestas,Suspendhsse potenai</p>
        <p><a class="btn btn-default" href="#" role="button">Read More</a></p>
    </div>
    <div class="col-md-4">
        <h2>Clean</h2>
        <p> Lorem ipsum dolor sit amet, consectetur adupiscing elt Aenean phairetra vanus maximuseCras cond imentum portotor cnima egestas,Suspendhsse potenai</p>
        <p><a class="btn btn-default" href="#" role="button">Read More</a></p>
    </div>
</body>

</html>